This study evaluates relationships among balance, biochemical, hormonal, kinetic and densitometric parameters of bone mineral metabolism in early adolescent girls. Comparisons will be made between White and Black girls and between healthy girls and those with precocious puberty. The specific aims of the project have not changed since the original project was begun. To summarize, these were to: 1)Assess changes in calcium absorption and bone mineral utilization during puberty in healthy girls; 2) To evaluate racial differences in pubertal girls in calcium metabolism; 3) To assess the changes in calcium metabolism associated with the precocious puberty; and 4) To assess the relationship between body composition changes during puberty and calcium metabolism.